v5.9.0

⚠️ Deprecations

• [deprecation] Several utility functions from src/language/utils.ts have been deprecated (#3476)
• [deprecation] Linting non-existent files now outputs a warning. This will be an error in TSLint 6. (#3313)

Configuration inheritance changes

Significant changes have been made to configuration inheritance to address a long-standing UX issue around defualtSeverity: #2569.

defaultSeverity defined in a tslint.json file will now override the defaultSeverity value defined in any configurations you are extending.
This means that any rules specified in the base configurations can now take on a new defaultSeverity if you so choose. If you extend multiple
configuration files, the defaultSeverity defined in the last one wins.

In practice, this allows users to, for example, more easily use the built-in TSLint configurations (tslint:recommended, tslint:latest, tslint:all)
and treat all errors as warnings instead of errors.

For more details, see the relevant PRs:

• Override defaultSeverity defined in extended configs (#3449)
• Inherit defaultSeverity and apply it to preceding base configs (#3530)

🎉 Features

• [feature] Support yaml configuration files (#1598) (#3433)
• [new-fixer] file-header (#3475)
• [new-rule] no-dynamic-delete (#3573)
• [new-rule] prefer-readonly (#2896)
• [new-rule] newline-per-chained-call (#3278)
• [new-rule-option] "temporalDeadZone" for no-shadowed-variable to ignore shadowing in the temporal dead zone of classes, parameters, enums and variables declared with let or const
  (#3389)
• [new-rule-option] "shorthand-first" for object-literal-sort-key (#3607)
• [new-rule-option] Add support for an ignore pattern for max-line-length (#3099)

🛠️ Bugfixes & enhancements

• [bugfix] Update commander.js dependency to prevent users from transitively installing a buggy 2.12.0 release (#3510)
• [bugfix] --project excludes all files of external dependencies (#3320)
• [bugfix] Show errors when tsconfig.json is invalid (#3410)
• [bugfix] no-implicit-dependencies don't crash on malformed package.json (#3373)
• [bugfix] strict-type-predicates allows comparing typeof result with non-literals (#3542)
• [bugfix] no-redundant-jsdoc fixed crash on unhandled tag (#3414)
• [bugfix] object-literal-sort-keys fixed regression that effectively disabled the rule with \r\n line breaks (#3427)
• [bugfix] curly fixer now correctly handles comments (#3473)
• [bugfix] no-unsafe-any fixed false-positive with namespaced types (#3487)
• [bugfix] Removed potentailly dangerous fixer for no-any (#3486)
• [bugfix] no-unnecessary-type-assertion fixed false negatives for types with numeric keys (#3468)
• [bugfix] callable-types adds parentheses when fixing a type literal inside an array type (#3440)
• [bugfix] no-unsafe-any allows spreading an any value into an object (#3439)
• [bugfix] no unnecessary whitespace before argument in callback functions fixed with arrow-parens fixer (#3618)
• [bugfix] prefer-const false negative with index signature named like a variable (#3385)
• [bugfix] whitespace rule checks property declarations if "check-decl" is enabled (#3546)
• [bugfix] Using ternary operator for calling super() now passes no-duplicate-super rule. (#3544)
• [bugfix] no-shadowed-variable now excludes declaration files and ambient modules (#3387)
• [bugfix] no-duplicate-imports Allow duplicate imports from separate ambient module declarations (#3398)
• [bugfix] await-promise correctly recognises classes extending Promise (#3383)
• [bugfix] prefer-conditional-expression: don't repeat error on nested if statements (#3528)
• [bugfix] completed-docs: don't require documentation on methods in object literals (#3532)
• [bugfix] one-line fixed crash on syntax error in class or interface (#3538)
• [bugfix] no-redundant-jsdoc allow @template tag if it has a description (#3415)
• [bugfix] Fix condition for deprecation of typeof-compare (#3429)
• [enhancement] Better error message for files not contained in the project (#3313)
• [enhancement] "properties" option for completed-docs rule now checks getter and setter accessors. (#3497)
• [enhancement]: no-magic-numbers ignores parseInt radix parameter (#3536)
• [enhancement] Avoid duplicate I/O when using --project option (#3313)
• [enhancement] clicking the filename in stylish-formatter's output jumps to the first failure in that file. (#3491)
• [enhancement] ban-comma-operator ignores comma operator inside for-loop incrementor (#3485)
• [enhancement] space-within-parens updated to always allow empty parentheses (). (#3513)
• [enhancement] Better error message syntax for completed-docs modifier lists (#3379)
• [enhancement] Improve failure message & docs for ban-comma-operator (#3384)
• [enhancement] Output code warnings in yellow instead of red for codeFrame formatter (#3402)
• [enhancement] Converted completed-docs rule to use a function instead of a walker (#3466)
• [docs] ban-comma-operator: fix metadata, list as "functionality" rule (#3612)
• [docs] Enhance no-use-before-declare documentation to clarify the rule's status (#3520)
• [docs] Enhance await-promise options documentation (#3519)
• [docs] Add hasFix metadata for the indent rule (#3529)
• [docs] Clearer rule description for no-irregular-whitespace (#3627)

Thanks to our contributors!

• Klaus Meinhardt
• Josh Goldberg
• Chris Barr
• Nathan Shively-Sanders
• Jeremy Morton
• Sergey Koshechkin
• Daniel Kucal
• Eric Smekens
• Johannes Choo
• Elena Vilchik
• Eugene Timokhov
• Carlo Bottiglieri
• reduckted
• Glavin Wiechert
• jbsingh
• Mateusz Witkowski
• HideDev
• Bruno Lemos
• aervin_
• Roman
• Ryan Waskiewicz